The present invention relates to codes and is concerned particularly with codes having two parts, which two parts are associated with each other.
Codes that are graphically represented and machine-readable are well-known. Such codes are commonly used on consumer goods and commercial products and when read may provide information relating to the cost, line item description, or origin of the product, for example. These types of codes may be used for automating check-outs at supermarkets, for stock control purposes or for verifying the correct product is in the correct packaging. More complex machine-readable codes of this type may be used as a security feature on certain consumer products such as pharmaceuticals, alcohol, tobacco and the like or for documents of high value such as currency, bonds, tax stamps, travel documents and identification cards to prevent counterfeiting, pass-off and diversion. There are a number of different types of code formats commonly in use; these include alphanumerics, linear barcodes and two-dimensional barcodes. Known barcodes include: Data Matrix, PDF-417, Micro-PDF-417, QR Code, MaxiCode, Codabar, RSS, EAN 128, UPC and Pharmacode. A major disadvantage of these types of code is the ease with which they may be copied. A further disadvantage is that a valid code may be guessed and constructed since the codes are based on algorithms which are in the public domain. Information which is encoded within the code can be derived, even if the data is encrypted, without reference to any database. The data may be used or manipulated for unauthorised purposes; this greatly reduces their effectiveness as a security device or track and trace device. The use of Data Matrix and PDF 417 codes as low cost track and trace devices is beginning to be trialled in some consumer goods sectors. They have a large enough data capacity to carry rudimentary information about the product history of the individual item, as well as its destination and customer details. However, their poor security will always limit their usefulness in the track and trace market.
One sophisticated type of machine-readable code is described in our UK Patent no GB 2383878 (the entire contents of which are incorporated herein by reference) and commercially available under the trademark FractureCode®. Advantages of this type of coding technology over other commercial machine-readable coding systems include the ability to generate a very high number of pseudo-random unique codes, making it impossible to guess the next code in the sequence. Another major advantage is that the code itself carries no data and no data is required to generate the code at the time the code is printed. This renders the code meaningless, or abstract, until the moment it is used.
Articles, such as consumer products or their packaging, are marked with such codes. In order to obtain information about the article the code must be read by a machine, which first performs a scanning operation to acquire digitally an image of the code. The image is then processed electronically to derive, via the application of an algorithm, a unique alphanumeric descriptor that may be used to look up data, which was previously associated with it, in a database.
The code is typically located on the surface of an article and comprises a unique graphical pattern, such as lines, dots or ellipses, with an area of this pattern delimited by a rectangular box, or some other boundary means, to form a code window.
It is particularly difficult to copy this code for a number a reasons. Firstly, it is difficult to reproduce the code with the degree of accuracy required, such that a reading machine would be unable to distinguish between the line position of an original code and that of a copy and would generate the same alphanumeric descriptor as would have been generated when scanning the original code. This feature is partly a function of the level of detail of the code. Secondly, many of the codes are no more than 1 mm by 1 mm in area and may be printed in ultraviolet inks, infrared inks or other covert security inks.
Although these types of code are very secure indeed, in some situations when they are used as a track and trace device they have a disadvantage when compared to barcodes in that data associated with the code can only be obtained by reference to a database. It is therefore desirable to provide a code which cannot be replicated and from which data can be directly derived.